FS45 SBC doesn't release RSTB issue

[snaku_lee]

Hi,

I am using FS4503 SBC, and I use IO_0 and IO_2 as wakeup signals. I got a problem is that if the IO_2 has 5V input first, then gives 12V to VSUP to turn on SBC, the SBC will not release its RTSB pin, then my MCU can't boot.

And this problem doesn't happen when the first time I power on the SBC, but it happens on 2nd, 3rd... when I turn on the SBC while the IO_2 has 5V. If IO_2 has no input voltage, then SBC will release the RSTB pin, and the MCU can boot and initialize SBC correctly.

One more thing, when IO_2 has 5V input signal but no power given to VSUP, I can measure 0.3V on the SBC VDDIO pins.

Snaku 

[guoweisun]

You mean first time IO_2=5V then VSUP=12V,the SBC can start up,but second or third time do the same operation RSTB can't release,right?

If so, please wait for 8s at lease, when you second time to do so.

[snaku_lee]

Hi Guoweisun,

Yes, the first time IO_2=5V then VSUP=12V, the SBC can start up, then keeps IO_2=5V, just turn on/off 12V, RSTB can't release.

And I tried to turn off 12V for more than 8 seconds, then turn on 12V, RSTB still keep LOW.

[guoweisun]

In the first time,do you get any fault flag  in SBC?

[snaku_lee]

Hi Guoweisun,

1. Do you have recommend registers should I read when the first time power up SBC?

2. Does IO_2 & IO_3 are used for FCCU function after SBC reset? if yes, what happens if FCCU fails?

Regards,

Snaku

[guoweisun]

Hi

1. Do you have recommend registers should I read when the first time power up SBC?

[gw]DIAG_VPRE/DIAG_VCORE/DIAG_VCCA/DIAG_VAUX/DIAG_VSUP_VCAN/DIAG_CAN_1/DIAG_CAN_2/DIAG_SPI

2. Does IO_2 & IO_3 are used for FCCU function after SBC reset? if yes, what happens if FCCU fails?

[gw]Yes it used for FCCU default, FCCU fail will be reported by DIAG_SF_IOs register and it will affect on the RSTB/FS0B.

[snaku_lee]

Hi GW,

When the 1st power on, MCU read below registers' values,

FS45_FS_INIT_FSSM_ADDR [0x25]  = 0x08

FS45_M_DIAG_VPRE_ADDR [0x0C] = 0x40

FS45_M_DIAG_VCORE_ADDR [0x0D] = 0x00

FS45_M_DIAG_VCCA_ADDR [0x0E] =0x00

FS45_M_DIAG_VAUX_ADDR [0x0F] = 0x00

FS45_M_DIAG_VSUP_VCAN_ADDR [0x10] = 0x00

FS45_M_DIAG_SPI_ADDR [0x13] = 0x00

FS45_FS_DIAG_SF_IOS_ADDR [0x2D] = 0x00

And I find more symptoms of this issue,
1. While IO_2 = 5V, let SBC enter low power mode (sleep), then wake up by IO_0, this issue will happen too.

2. When this issue happens (SBC doesn't release RSTB), remove IO_2, then SBC will release RSTB.

Regards,

Snaku

[guoweisun · Accepted solution]

1:I confirmed if IO_X below 8V,the SBC can start up normally.

In you case, do you know which phase get stuck during start up? you can match below startup timing? perhaps ABIST1 detect error.

2:If you set IO_2=0 ,IO_0=5V,then power the SBC does it can startup each time? 

[snaku_lee]

Hi GW,

Yes, you are right, I find the problem is my IO_2 signal too high, 8.4V, not 5V. After reduce the IO_2 wakeup signal voltage, the issue solved.
Thanks for your help.

Snaku